Air-waterborne vessels



Dec. 2, 1969 R. M. STEPHENS AIR'WATERBORNE VESSELS' Filed May 11, 1966 5Sheets-Sheet, 1

INVENTOR Dec. 2, 1969 R. M. STEPHENS AIR-WATERBORNE VESSELS 5Sheets-Sheet 2 Filed May 11, 1966 INVENTOR Dec. 2, 1969 R. M. STEPHENSAIR-WATERBORNE VESSELS Filed May 11, 1966 5 Sheets-Sheet 5 INVENTQR Dec.2, 1969 R. M. STEPHENS 3,4

AIR-WATERBORNE VESSELS 5 Sheets-Sheet 4 Filed May 11, 1966 fig gw E E Ev E NyE NTOR flG. l5

Dec. 2, 1969 R. M. STEPHENS AIRWATERBORNE VESSELS' 5 Sheets-Sheet 5Filed May 11, 1966 fie. l4

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INVENTOR United States Patent US. Cl. 114-67 23 Claims ABSTRACT OF THEDISCLOSURE An air-waterborne vesselin which a singular volume ofcontained static air is contracted by the displacement of said vesselwithin inverted open bottom pontoons spacedly disposed catamaran fashionon either side of the hull, on the inverted bowl principle, substitutingair friction for the normal wetted friction to which marine vessels aresubjected, said vessel-fills the roll of a fast freighter as distinctfrom the tramp, steamer. Same principle is utilised in open bottomcompartments on the underside ofa fully displaced cargo vessel, the airvolume of said compartments being automatically maintained by the levelof the water in said compartment.

In recent. years the hydrofoil and the air-cushion vehicle have come tothe fore as high-speed nautical vessels. The hydrofoil uses vast amountsof power to surface and maintain essential speed, while the air-cushionvehicle of medium size is limited to light loading of some 20 lbs. tothe square foot about half the weight an automobile presents. Presentinvention seeks to increase this loading seven to ten times.

The principle incorporated is that simply suggested by an inverted bowlon water where it weight is supported by static air slightly compressedthereby and trapped within, with a minimum of displacement. Incidentallyit will be observed that the-bowl becomes highly unstable, the airescaping if the bowl is slightly tilted. It is the purpose of thisinvention to overcome this kind of instability, by design hereinafteroutlined, more particularly as it relates to vessels solely supportedabove a water supporting-surface by a volume of contained static air,also to vessels which by designation will become part-displacementvessels in which a portion of the weight of the vessel is supported bycontained air. It will also involve vessels fully displaced, in whichthe water skin friction on the bottom of the hull is replaced-by'airskin. friction. This latter group includes-.canal'and oceangoing barges.

A brief description of applicants vessel solely supported by containedstatic air follows, including an explanation of the principles involved.

7 Supported on long inverted catamaran type pontoons having an openbottom and straddling the vessel, its hull rides above the water withoutdisplacement other than the sidewalls of the pontoons and the gatingthereto. The interior space of these pontoons extends verticallypossibly the full height of the vessel or alternatively between a doublefloor of the vessel to a point midway of its beam. This space ispartitioned transversely into a number of compartments each air-sealedfrom its neighbor. These transverse partitions reach down to theinterior waterline, which incidentally when the vessel is fully loadedwill be several feet below sea level, and at that point they terminatein a horizontally hinged flap flexibly resisting the passage of seawater. These flaps are air-sealed at the sidewalls of the pontoons sothat each compartment is completedy isolated from the adjoiningcompartment. The stem and stern of the pontoons are flexibly gated andconstructed in such a way as to keep the contained air from escapingwhile allowing the sea water to pass through. However to do. thiseffectively the lower Patented Dec. 2, 1969 gates at both stem and sternwill need the assistance of coil springs, the water and air pressures atthis point being more or less equal. These gates are air-sealed to thesidewalls of the pontoons by rubber sheeting either bonded or rivetted,the ends of the gates near the sidewalls are cut at an angle to allow itto swing freely with the rubber sheeting proportionately stretched.Incidentally since there might not be enough room in a canal for a bargeto turn around the gates should be capable of swinging both ways fromthe vertical so that the barge can move in reverse direction.

An alternative to the mechanical method of gating is illustrated inFIGURE 8 and provides for water at a pressure of approximately 300 lbs.per square inch being forced downwards as a short jet sheet fromsuperimposed tubes transversely disposed at both stem and stern of thepontoons to impinge on the next lower tube. While no precise informationis available it is here assumed that any jet sheet of water wouldrespond as any cantilever beam and deflect as the cube of the span. Asingle high velocity jet sheet was proposed for the Hovercraftaircushion vehicle riding on a two foot cushion of air. The proposal waslater rejected as being ineffective and uneconomic in the use of waterand confined the vessel to operating over water. As here proposed aseries of jet sheets reduced in length to eight inches would under thecube law, experience a deflection amounting to one twentyseventh of theexample cited. This arrangement of multiple jet sheets would readilyyield'to the inrush of water, but with air now slightly compressedweighing 600 to 700 times lighter than sea water it is considered thecontained air would be held back without loss.

It is anticipated the buoyancy compartments of vessels solely supportedby contained air will be subjected to minor variations in static airpressure in a choppy sea. In order to minimze the effect of thesechanges, an automatic air-relief valve is located in the outer wall ofeach compartment to guard against undue over-pressure, while an aircompressor with storage means furnishes a ready supply of air toreplenish incidental air losses. However for reasons to be explainedlater a valve manually operated by remote control can when desiredreduce the volume of air in each compartment, and should such action betaken, as might be the case with lighty loaded vessels, it will be foundthat the buoyancy compartments due t the pumping action of the waveswill add air to its volume rather than lose it. In the interest ofstability all the vessels solely supported by contained air will havewater'ballast ducts in one form or another. If the ducts are locatednear the sea level waterline they will need to be gated to prevent ordelay the loss of water therefrom should the vessel unduly tilt. In theembodiment covering a shallow draft vessel intended for up-river use andresembling the vessel illustrated in FIGURE 10 except that it would befully and not partially gated at the ends, the principle of waterballasting is adopted in part, the pontoon itself being utilized forthis purpose rather than adding a separate duct. To attain this end andto strengthen the pontoon against sand and mud bars, the bottom edges ofthe pontoon sidewalls are joined, and When fully gated at the ends forman enclosure suitable for the retention of water ballast. However, toavoid a buildup of air pressure within the pontoon buoyancy compartmentdue to the inrush of sea water therein the bottom of the pontoon isperforated in numerous places thus normalizing the interior water level,yet retaining to a modified extent the effectiveness of the ballastingprinciple.

In the embodiment illustrated in FIGURES 2 and 3 the water ballastingduct is shown paralleling the pontoon at the side rather than at thebottom with the object of minimising the draft. Superimposed upon thisduct at the four corners of the vessel is a streamlined contained-airstabilization compartment. Together they can form a composite waterballast unit. The stabilization compartment however is supplemental andwould be used when Windstorm conditions were imminent. It could ifdesired be omitted from the design. These stabilization compartmentswould be closed at the top and open into the water ballast duct but at apoint well below the sea level waterline, the duct being gated. When itis desired to use these stabilization compartments they would be whollyor partially exhausted of air by vacuum means causing them tosimultaneously fill with water or to the level desired. In amodification of this latter arrangement the gating could be omittedprovided the duct was located along the bottom half of the pontoon. Itshould be pointed out however that were this duct to be without gatesthe water would pour out directly as the pontoon rose above the sealevel waterline, at the same time draining the water from thestabilization compartment and at a time when its need was greatest.While this situation is unusual, design must be related to the worstconditions the vessel would have to meet. However it is possible that bymaking prior full use of the stabilization compartments the situationjust described might never arise.

Should it be decided as previously suggested to dispense with thestabilization compartment and with it that arrangement of water ballastduct with which it co-operates, the alternative would be the placing ofthe ballast duct directly below the pontoons as illustrated in FIGURE10. In this case the duct portion would not need to be gated at the endsbecause of the depth at which it was situated and would have theadvantage of simplicity and added capacity. In each duct at any givenmoment water in the amount of 20 percent of the loaded weight of thevessel would be continuously entrained therein adding nothing to themass of the vessel, the water being transitory and being subject tovertical inertia forces only, the only penalty, apart from the weight ofmetal being an increase in the wetted area subject to skin friction.

In another embodiment involving a vessel partly displaced and partlysupported by air as illustrated in FIG- URE 4 the vessel has an innerand an outer buoyancy compartment both of which extend almost the fulllength of the vessel. The outer compartment is designed to functionalternatively as a water ballast stabilization compartment but only whenbad weather is imminent. The amount of water allowed in would vary withthe severity of the storm. This outer compartment would be partitionedin the same way as the inner compartment, as previously described, aswell as being gated at the ends. It will be recognised that in thisparticular form the water ballast taken in adds to the mass of thevessel as distinct from the transitory form of water ballastingpreviously outlined and illustrated in FIGURE 10. It should also bepointed out that the problem of admitting and ejecting water from thestabilizer compartment is very simply accomplished and with very littleeffort by sucking the air out of the compartments, which actionsimultaneously draws in the sea water to occupy the space vacated. Laterby opening a valve at the top of the compartment and letting air in, thesea water will fall due to the influence of gravity. It is consideredthat with partly displaced ocean going vessels and the storm conditionsoccasionally experienced, possibly of hurricane velocity, thesearrangements lend themselves admirably to the situation.

A cardinal feature of the design is the extension of the pontoon spacevertically the full height of the vessel constituting itself as abuoyancy compartment. This height of air space permits a rise of waterwithin the pontoon to a much greater extent for the same increase ofloading pressure than if the space did not exist, and a marked rise ofthe water level within the pontoon is desirable if the spilling of theair is to be avoided. This objective, as mentioned earlier, is enhancedin the case of vessels solely supported by contained air, allowing themto settle lower in the water, by allowing some of the air now in a stateof compression to be exhausted from the buoyancy compartment. Howevervolume of buoyancy space is the criterion here not the height. Accordingto Boyles law for gases a ten percent increase in pressure isaccompanied by a reduction, amounting to one eleventh, of its originalvolume. Since in a selected instance we might desire a vessel loading ofone pound per square inch, or 15.7 lbs. per square inch absolute, thebuoyancy space will be reduced to 14.7/ 15.7 of its original volume andif the compartment was uniform in cross section and extended up for adistance of 16 feet the buoyancy space would contract approximately onefoot. In addition, this rise of one foot could be increased, first byexhausting some of the air from the compartment and secondly by designenlarging the buoyancy compartment above the sea level water line. Inthe instance selected, a pressure of one lb. per square inch or 144 lbs.per square foot would support a column of water 2 feet 3 inches highconsequently the water outside the pontoon would be that much higherthan the water inside and since the water inside has already risen onefoot by reason of the load compression, the water level outside wouldactually be 3 feet 3 inches from the bottom of the pontoon. It will beseen therefore that water entering at the stem of the pontoon willcascade down 2 feet 3 inches to the inside water level and should thevessel loading be increased to 2 lbs. per square inch or 288 lbs. persq. ft. the water would have to cascade down 4 feet 6 inches from theouter pontoon height of 6 ft. 6 ins., the vessel having settled afurther one foot with the increased compression, so that in the lattercase the pontoon should be at least 7 feet deep. It will be recognisedin these circumstances that all the water entering the pontoon will bedepressed by an amount equal to the normal displacement of the vesseland it is natural to assume that depressing this amount of water over amile run say would require the expenditure of considerable energy. Theultimate benefit of course would be that air friction had replaced waterfriction.

For obvious reasons the overwhelming majority of displacement vesselswill not have buoyancy compartments located on the sides but still couldbenefit from a reduction of skin friction on a large portion of thewetted surface on the underside of the hull substituting air frictionfor water friction particularly if the beam dimension was increasedrelative to the draft and adapted say to medium speed tramp vessels.River barges should find this arrangement most effective. In such casesa number of rigidly or flexibly gated shallow open-bottom ducts wouldextend the full length of the flat bottom portion of the hull, theflexible gates being spring-loaded at both stern and stem for thecontainment of the static air. However in the case of ocean-goingvessels these ducts would be transversely partitioned with a hinged flapat the inside waterline in much the same manner as the buoyancycompartments. These partitions would prevent most of the contained airfrom moving to the higher end during a pitching motion of the vessel.Some air will be lost in a rough sea but this can be replaced from acompressed air source piped into each compartment, the horizontalflexing of the partition being the means to open a valve on the airline. During storms the air supply could be cut off entirely. Existingvessels could be modified in a ship repair depot to incorporate theseshallow ducts, possibly building a false keel to better support it indrydock. Shallow ducts are not expected to be as effective in thereduction of drag as the deep buoyancy compartments but their locationat depth and the absence of extreme turbulence as it exists at thesurface should be a factor in its favor. Skin friction at cruising speedcomprises some 60 percent of the total resistance in a displacementvessel, however percent of that friction resides in the outer turbulentwater boundary layer and the other 10 percent in the laminar sublayernext to the hull. This turbulence generates within the sea water aconsiderable momentum transfer, the visible widening extent of whichincreases with the speed of the ship and creates the drag upon it. Itwould appear that a great reduction in resistance would be effected ifthis momentum transfer could be strictly confined to air rather thanwater since in this situation the air now slightly compressed weighs onefive-hundredth to one six-hundredth that of sea water. However it wouldseem that a minimum thickness of air cushion would be an essentialcriterion, to be determined empirically.

Aircraft carriers such as are built today are both large and expensiveand consequently limited in numbers. Since there is every prospect thatwith attention now being given to the development of aircraft havingV.T.O.L. (vertical-take-off-and-landing) and S.T.O.L. (short-takeotfand-landing) characteristics, that a new smaller aircraft carrier insufficient numbers to provide wide global dispersal will be evolved.These carriers would have a shorter and relatively wider flight deck.Present application'anticipates such a vessel almost wholly. supportedby air with only enough displacement to provide for efficient waterpropulsion, in other words a part-displacement vessel. Such a vesselwould minimise all phenomena now experienced due to displacement such asthe bow wave, the extensive belt of turbulence around the ship .with itsconsequent high drag and the eddies which fol low in'itswake. Such waveaction as does occur at the bow of theproposedvessel will be confinedbetween the sides of the hull and the side of the adjacent buoyancycompartment. The designed extra width of this aircraft carrier would befully .utilized by buoyancy compartments which would not only supplantair friction for water friction, but would also function as lateralstabilize'rs, a downward tilt on the starboard side for instance wouldcompress the contained air still further on that side creatingadditional buoyancy, while reducing the amount of buoyancy on theportside, the added leverage exerted by the buoyancy compartments inthis design being a plus factor. Such a vessel could if thoughtnecessary make use of the outer buoyancy compartment as a water ballaststabilizer .compartment as previously described and illustrated inFIGURE 4, such use however would only occur during storm conditions. Thesubstitution of air friction for water friction over sucha large areawould add considerably to its speed enabling it to run ahead of thestorm should one beimpending. With regard to the utilization of theextra space provided by the enlargement of the buoyancy compartments, itis conceivable that if the increase in air pressure, which would notexceed 4 lbs. per. square inch could betolerated for long periods, thecompartments could be .used as repair and service. rooms with light,heatand power provided. Perforations at the periphery of the floors wouldprevent interference with the buoyancy principles. A double doorair-lock would allow communication between. the compartments and therest of thevessel. A decompression room might be found necessary. I v

, Propulsion of air supported vessels is dealt with in several waysvarying with the uses and the .size of the craft. A high speed vessel ofrugged construction serving in the capacity of a small aircraft carrierfor use of aircraft in the V.T.O.L. and S.T.O.L. categories, not havinneed for large quantities of steam for catapulting operations, wouldhave its flight deck almost clear of obstacles, having a marine enginefor economical cruising and being supplemented by a number of by-passgas turbine engines of immense power and light weight for the occasionalburst of speed. With similar sized vessels in commercial operation whereeconomy had to' be exercised both in capital expense and operating cost,a marine engine of ample proportions would provide sole propulsion.

Shown in FIGURE 3 is a pivotal engine compartment providing excellentmanoeuvering capability and a shorter radius of turn, the compartmentserving as a rudder. Small light vessels would most likely use airpropellers much as air-cushion or ground effect machines do but in thisservice.

instance rudders for directional control would be hinged at the stern ofthe pontoons.

Vessels of the type solely supported by contained static air will beinitially confined to rivers and sheltered seas and when more knowledgehas been acquired as to their behavior the design of larger and morerugged craft would be undertaken. The greatest economic gain from theseimprovements would appear to accrue to oil tankers, grain vessels andtramp steamers on long voyages, these vessels having shallow ducts onthe bottom of the hull. In the past little restraint has been exercisedon the draft of these vessels. If the contentions here avowed are fullywarranted, emphasis can now be placed on increasing the beam relative tothe draft, since this is the area where the greatest reduction of skinfriction would obtain, the wider the beam the greater the gain.

It is natural that a new type of vessel such as this is will experienceproblems peculiar to itself which will become more apparent at highspeeds and in rough seas and must be dealt with on a trial and errorbasis. Most of the formulae and technology governing displacementvessels will have little place in this design and new criteria will haveto be established.

The illustrations shown do not exhaust the list of possible embodimentssince an interchange of elements and the combinations thus effected willbe considerable and I desire only such limitation on construction aslies within the range of the principles enunciated and the scope of theappended claims.

An object of the invention is the creation of an airwaterborne vessel inwhich air in a static condition intervenes for support between the seaWater and said vessel to avoid the immergence of said vessel.

An additional object is to substitute air friction for water frictionwherever possible in the support of airwaterborne vessels therebyincreasing the speed for the same expenditure of energy.

A further object is to increase the relative loading of air-waterbornevessels to reduce their cost of operation. A further object is toinstitute a fast marine cargo Another object is to effect economy in theamount of air used in the support of air-waterborne vessels.

Another object is to reduce the amount of skin friction resistance ofdisplacement vessels by increasing the amount of horizontal supportsurface relative to the vertical surface, Within the limit of stabilityand other pertinent considerations by the intervention of air betweenthe water supporting surface and the horizontal surface of the vessel.

A further object is the aquisition by air-waterborne vessels of thebenefit of water ballasting without adding same to the mass of thevessel.

Another object is the reduction by mechanically flexed gating as well asby hydraulic gating, the impact ofthe sea water on air-waterbornevessels when in motion and the retention of contained static air by suchmeans.

A further object is the elimination of the undesirable yaw movement ofvessels supported solely by contained static air.

Another object is the elimination of the accretion of barnacles to theunderside portion of the hull of a marine vessel by the intervention ofair between the water supporting surface and the bottom of the hullwiththere- 'sulting reduction of drag on the ship and the recurring needfor drydocking facilities.

Embodiments of the invention will be described with reference to theaccompanying diagrammatic drawings in which:

FIGURE 1 is a cross-sectional side elevation of a lightdraft vessel withthe outer panelling removed to show the bulkheads.

FIGURE 2 is a plan view of the same vessel showing the cut-away line anddirection for the view in FIGURE 1.

FIGURE 3 is a front view of the same vessel with the bottom edge of thepontoon unit being joined, also the positioning of the pivotal enginecompartment.

FIGURE 4 is a cross-sectional view amidship of a partdisplacement vessellooking toward the stern showing the water ballast and stabilizationcompartment contiguously arranged and with the buoyancy compartmentcontainedair area indicated by the relative water levels, also theextension of this buoyancy area horizontally above the deck of thevessel.

FIGURE is an enlarged cross-sectional broken view bottom edge of thepontoon unit being joined, also the gating of the lower end of abulkhead.

FIGURE 6 is a front view of the stem gating in FIG. 5.

FIGURE 7 is an interior view of the stern gating of a buoyancycompartment looking towards the stem from the second last bulkhead ofthe vessel in FIGURE 1.

FIGURE 8 is a cross-sectional view of an alternative hydraulic method ofstem gating.

FIGURE 9 is a cross-sectional view of the stem gating of a light-draftriver vessel or barge.

FIGURE is an alternative arrangement to FIG. 1 eliminating thestabilization compartment and positioning the open ended water ballastduct beneath the pontoon buoyancy unit.

FIGURE 11 is a fragmental view of an alternative method of mechanicalgating showing spring-loaded freely hinged gates at stem of pontoon.

FIGURE 12 is a cross section of compositely constructed tube forhydraulic method of gating.

FIGURE 13 is a cross section plan view of the hydraulic tube.

FIGURE 14 is a plan view, looking up, of the ducting on the underside ofthe hull of a barge or displacement vessel.

FIGURE is a broken cross-sectional side view of the shallow ducts of thevessel in FIGURE 14.

FIGURE 16 is a detail of the flap activating mechanism of the air linevalve of the vessel shown in FIGURES 14 and 15.

The embodiment illustrated in FIGURE 1 shows the hull 1 streamlined andelevated above the sea-level waterline and spanning inverted catamarantype pontoons 2. The pontoon air space extends vertically the fullheight of the vessel to create an enlarged buoyancy space which issubdivided by bulkhead or partitions 3 into compartments 4 eachair-sealed from its neighbor. The partitions 3 extend down almost to theinterior waterline where they terminate in a flexed flap 5 air-sealed byrubber sheeting 6 to the sidewalls 7 of the pontoons 2 and extend downbelow the said interior waterline to complete the air-sealing of thebuoyancy compartments 4.

With the object of maintaining the air pressure within the buoyancycompartments 4 at a desired level, each compartment 4 has a simpleautomatic over-pressure relief valve (not shown) on its outer wall, thewall being eliminated by the cut-off in FIGURE 1, also a valve (notshown) on its inner wall remotely controlled and linked to an aircompressor source for the replenishment of incidental air losses, also aseries of air ducts 8 of small dimension linking the opposite numbercompartments 4 as disposed about the major and minor axes of the vessel.This air duct system 8 is specially designed for vessels of light draftand is intended to provide an automatic fourpoint equalization of airpressure in any four buoyancy compartments 4; excessive over-pressurebeing relieved by the relief valve previously mentioned. FIGURE 1 alsoshows the location of the gates 9 at the stem of the pontoon 2 alsoshown in greater detail in FIGURES 5 and 6. Designed to reduce theimpact of the sea water on the pontoons 2 this series of inclinedsuperimposed gates 9 flexibly hinged at 10 are air-sealed by rubbersheeting 6 in the same manner as the flexed flap 5 at the lower end ofthe partitions 3. However in this instance a rubber buffer 11 at thebottom of the gate '9 bears against the next lower hinge 10 to seal thegates 9 against air loss when shut by internal air pressure. These gates9 are flexed to the horizontal position during the rapid inrush of seawater as the vessel is propelled forward. The lower of the gates 9 aretension spring-loaded since in the stationary condition the air andwater pressures are substantially in balance at this point and theassistance of springs 12 is needed to make their action positive. Asingle gate 13 hinged at the stern of the pontoon 2 at a point above theinterior waterline has its upward movement resisted by springs 12.FIGURE 6 shows a front view of the gates '9' in a slightly openposition, the diagonal cut of the gates 9 is seen allowingthe rubbersheeting 6' to fully flex and evenly stretch without obstructing themovement of the gate 9 to the horizontal position. When the water is notpassing through the gates 9 the interior air pressure keeps them shut.In FIGURE 7, an interior view, shows coil springs 12 secured to the stemgate 13 capable of exerting strong pressure against the sea flow andstatic air pressure which at this point are additive. In this case thebottom of the stern gate 13 terminates well below the interiorwaterline. A modified form of mechanical gating is illustrated in FIGURE11 and shows a freely hinged flap 14 unsealed except when shut impingingagainst a rubber buffer 15 bonded or rivetted to the sidewalls 7 of thepontoons 2 and the next lower hinge 10, and having the advantage ofsimplicity in form and in action but with increased risk of air loss.

An alternative to the mechanical method of gating is illustrated inFIGURE 8 and shows a series of vertically spaced tubes 16 spanning thesidewalls 7 of the pontoon 2. A thin jet sheet of water is dischargedfrom the underside of the tube 16 to impinge on the upper roundedsurface of the next lower tube 16. These tubes 16 are shown in moredetail in FIGURES 12 and 13, preferably streamlined and of compositeconstruction in order that the slit 17 on the underside of the tube 16be continuous. Internal braces 18 join the lips of the slit 17 to giveit the necessary strength to resist the great pressure within. A seriesof deflectors 19 staggered within the tubes 16 change the direction ofthe hydraulic flow through degrees to issue at the slit 17 as a thin jetsheet.

Water ballast forms an integral part of a number of the embodimentsillustrated, varying in position and relative size in accordance withthe extent of the need and the territorial area in which the vesseloperates. Excluded from the category are fully displaced vessels as wellas barges.

FIGURE 2, which should be studied in conjunction with FIGURE 3 is a planview of the vessel in FIGURE 1. FIGURE 2 shows a water ballast duct 20adjoining the pontoon 2 on the outside and extending its 'full length.Four stabilization compartments 21, one at each corner of the vessel aresuperimposed upon the water ballast duct 20, the two structurallyforming a composite unit. However, the duct portion 20 functionscontinuously while the stabilization compartment 21 operates only on asupplemental basis. The submersed portion of the stabilizationcompartment 21 is streamlined and not open directly to the sea flow,this latter function being restricted to the ballast duct portion 20. Itwill be observed that this lower duct 20 is gated at both stem and sternwith the object of retaining the water ballast should the pontoon 2 beunduly elevated above the sea level which action should not be confusedwith the normal roll of the ship. Stem gates 9 and stern gates 13 do notinterfere with the transitory nature of the ballast flow until such timeas this undue tilting occurs, thus creating a vectored inertialcomponent. The bottom edges of the pontoon 2 of this embodiment arejoined for added strength and this arrangement makes it mandatory, sincethe pontoon 2 is gated, to perforate the bottom surface of the pontoon 2in numerous places in order to keep the interior water down to itsnominal level. A small dimension air duct 22 links all four stabilizercompart- 9 ments 21 with a vacuum source (not shown) but which may bethe inlet of the air compressor.

In FIGURE 4, a part displacement vessel, extended use by necessity ismade of the air buoyancy facilities not only providing additionalsupport but added leverage. The outer buoyancy compartment 4 serves onoccasion as a supplementary stabilization compartment 21 since as anocean-going vessel it may be called upon to meet very severe stormconditions. In such situations the air is sucked out of the compartment4 replacing it simultaneously with sea water and so functioning ascompartment 21. However it is quite probable that under ordinary roughweather conditions reliance will be placed on the added leverage of theouter compartment 4'functioning in the interest of buoyancy to furnishall the additional stability required. In FIGURE 4 the buoyancycompartment 4 is shown extending over the deck of the vessel, howeverthis extension must terminate amidships otherwise its ability tovfunction as a stabilizing factor will be negated. These buoyancyextensions could, if used, be intermittently spaced between deck hatchesor oil inlet valvesin the case of oil tankers.

In FIGURE 10 the water ballast duct is set immediately below the pontoon2 portion of the buoyancy compartment, no diaphragm separates them. Thisparticular embodiment is designed to operate in sheltered seas whereanabs'ense of draft limitation such as would be necessary with up-rivercraft, contributes favorably to the design. The greater depth at whichthe ballast duct 20 is set in this case eliminates the need todownwardly extend the stem gates 9 and the stern gates 13 to cover theballast duct 20. The free flow of water through'the duct 20 thuspermitted, avoids the water and air pressure build-up which would occurif the ballast duct 20 were gated. Perforating the bottom of the ballastduct 20 to normalize the pressure situation within the pontoon 2 is thusobviated.

The embodiment shown in FIGURE '14 has for its object the replacing ofwater skin friction with air skin friction. The drawing shows a seriesof shallow longitudinal open bottom ducts 23 extending the length of thefiat bottom portion of the hull 1. Rigid transverse walls 24 angularlydisposed to the sea water flow at both stem and stern are air-sealedsecured to the hull 1 and sidewalls 25 of the air ducts 23 to ensure thecontainment of the air within the duct 23, said ducts being subdividedinto a multiplicity of air-sealed compartments 26 by transversepartitions 27 secured to the bottom of the hull 1 and the sidewalls 25and terminating in a flap 28 backwardly hinged at'a point above andextending below theinterior waterline to complete the air-sealing ofeach compartment 26. The purpose of the partition 27 is to prevent themobility of the air contained within the duct 23 during a pitchingmotion of the vessel. Each compartment 26 has valved communication withan exterior compressed air source for the replenishment of incidentalair losses..Air loss when of. consequence causes the sea water to risehigher withinthe duct 23with the result that the flap 28 will be flexedtothe horizontal by the sea water flow and in doing so activates aspringloaded valve 29 on the airline to admit compressed air into thecompartment 26 to make good the air loss. The compressed air must beinitially admitted to the compartments 26 at a greater pressure than thestatic pressure existing at the depth at which the ducts 23 arepositioned. At a depth of 10 feet in salt water the air will becompressed approximately 23'percent; at 20 feet, 38 percent; and at 30feet, 47 percent; the air being admitted to some desired level betweenthe hinge of the flap 28 and the bottom of the duct 23.

What is claimed is:

1. An air-waterborne vessel supported above water solely by containedstatic air which is contained above a water surface and within thesealed envelope of longitudinally disposed open bottom ducts, theirlower ex 10 tremity penetrating said water surface to form an enclosureon either side of the hull of said vessel, said ducts being gated atstem and stem to permit a one-way flow of seat water therethrough whilepreventing the escape of, said contained air therefrom, said ducts beingsubdividedinto segregated buoyancy compartments by vertical partitions,said longitudinal ducts sustaining said hull above the sea levelwaterline to avoid displacement of said hull, said longitudinal ductsfunctioning as inverted catamaran type pontoons, said partitionsterminating at said water surface by a horizontally disposed flapflexibly secured and responsive to the sea flow to complete. thesegregation of the said buoyancy compartments, said.

ducts having parallel sidewalls and having a gate at the stem endspanning said sidewalls and being flexibly air-sealed thereto, said gatebeing horizontally hinged above the sea level waterline and extendingabove and below said waterline, said gates at stem and stem beingdesigned to prevent the escape of said contained static air whilepermitting a one-way flow of sea water thereunder, said buoyancycompartments supporting the hull of said vessel above said water surfaceto avoid displacement of said hull.

2. An air-waterborne vessel as described in claim 1, said pontoonshaving parallel sidewalls and being gated at both stern and stern, saidgating at the stem comprising a series of superimposed horizontallyhinged flaps spanning said sidewalls and being flexibly air-sealedthereto and contact sealed when closed under pressure against the nextlower hinge, said series of superimposed flaps extending from a pointabove the sea level waterline to a point below the pontoon interiorwaterline, said gating at the stern comprising a spring loaded flapvertically pivotal about a horizontal axis and spanning .said pontoonsidewalls and being hinged above and extending below said pontooninterior waterline, said gates at stem and stern designed to prevent theescape of said contained static air while permitting a one way flow ofsea water therethrough and thereunder, said buoyancy compartmentssupporting the hull of said vessel above the water supporting-surface toavoid displacement of said the sidewalls of said pontoon buoyancycompartments being joined at the bottom, said pontoons having amultiplicity of perforations on its bottom surface below said pontooninterior waterline with the object of maintaining said interiorwaterline at its norm.

5. An air-waterborne vessel as described in claim 4, means contributingto the stability of said vessel, said means entailing the release of atleast ten percent of the air from within said contained static airspace.

6. A vessel as described in claim 5, having means for the replenishmentof incidental air losses, said means comprising air compression andstorage means with ducted valved communication manually operated byremote control to each said buoyancy compartment independently, eachsaid compartment having a valved vent remotely controlled permitting therelease of a measured quantity of said contained static air, and anover-pressure relief valve automatically activated.

7. A vessel as described in claim 6, each said pontoon buoyancycompartment having freely transmitted air ducted communication with thebuoyancy compartment oppositely disposed about both major and minor axesof said vessel for the purpose of equalizing air pressures laterally andlongitudinally to assist in the preservation of overall stability.

8. A vessel as described in claim 7, having transitory water ballastmeans associated therewith and disposed on both sides of said vessel.

9. A vessel as described in claim 8, said transitory water ballast meanscomprising a longitudinal duct contiguously disposed below each saidpontoon and forming a composite unit therewith, said duct portion beingopen at the top and ends and closed at the bottom.

10. A vessel as described in claim 9, said transitory Water ballastmeans comprising longitudinal ducts contiguously adjoining said pontoonbuoyancy compartments on the side and positioned below the sea levelwaterline, said ducts having horizontally hinged transversely disposedgates at stem and stem limited in the amount of their downward swing bya stop-rail, the upward swing of the gate at the stern being springresisted to retain said water ballast within said duct when elevatedabove sea level.

11. A vessel as described in claim 10, having stabilization compartmentsvertically disposed above and below the sea level waterline, closed atthe top and open at the bottom and being located one at each outercorner of said vessel, means to exhaust the air and means to release thewater from said stabilizer compartments, said compartments communicatingvertically with said water ballast.

12. A vessel as described in claim 11, having propulsion means integraltherewith, said propulsion being derived by air thrust while at sea andby water thrust while in port, means to surface said water thrust meansand means associated with said vessel and said water supporting-surfaceto directionally control the movement of said vessel.

13. A vessel as described in claim 12, the primary means of propulsionoperating in a water media supplemented on an intermittent basis by theair thrust of gas turbines.

14. A self-propelled air-waterborne vessel as described in claim 13,said water thrust means being contained within a streamlined compartmentextending below the hull of said vessel and being partly submersed, saidsubmersed portion of said compartment having means associated therewithfor the directional control of said vessel.

15. A vessel as described in claim 14, said streamlined enginecompartment being horizontally pivotal about a vertical axis, saidsubmersed portion of said pivotal compartment functioning whennecessary, as a rudder.

16. An air-waterborne vessel supported at sea partly by contained staticair and partly by displacement of said hull, having propulsion meansintegral therewith, said static air contained above a water surface andwithin a pair of longitudinally disposed buoyancy units havingsidewalls, and being closed at the top open at the bottom, gated at theends and straddling the hull of said vessel, said buoyancy units beingsubdivided into compartments by transverse vertically disposedbulkheads, each said compartment being air-sealed from the adjoiningcompartment, said bulkheads terminating at the buoyancy unit interiorwaterline in a horizontally hinged flap flexibly air-sealed to saidsidewalls to complete the air-sealing of said compartments, said gatingat both ends of said buoyancy unit being designed to prevent the escapeof said contained static air while permitting a one-way flow of seawater therethrough.

17. A part displacement vessel as described in claim 16, said buoyancycompartments having in addition a horizontal partition serving as afloor, said floor having a multiplicity of perforations at theperiphery, an airlock having air-sealed doors at each end of saidairlock communicating with and separating said buoyancy compartmentsfrom the rest of the vessel, means to prevent both air-lock doors beingopened at the same time, signal means associated with said door openingoperation and means to provide heat, light and power to said buoyancyunits.

series of superimposed horizontally hinged flaps spanning said sidewallsand being flexibly air-sealed thereto and contact sealed when closedunder pressure against the next lower hinge, .said series ofsuperimposed flaps at the stem extending from a point above the sealevel waterline to a point below said buoyancy unit interior waterlineand at the stern said series of superimposed gates-ex'-' tending aboveand below said buoyancy unit interior waterline, the lower of allsaidgates being spring loaded-* for the positive containment of saidstatic air. g

20. A vessel as described in claim 19, the gatingat the stern of saidbuoyancy unit comprising a single hori zontally pivotal spring loadedflap spanning the sidewalls of said buoyancy unit and being flexiblyair-sealed there-- below said to, 'said fiap being hinged above andextendingv buoyancy unit interior waterline. 1 i

21. A vessel as described in claim 20, having transitory waterballasting means associated therewith-comprising longitudinal open endedducts positioned below sea level on either side of said hull.

22. A vessel as described in claim 21, said water ballast meanscomprising a supplementary compartment contiguously paralleling saidbuoyancy unit above and below the sea level waterline, saidsupplementary compartment being closed at the top, open at the bottom,gated at the ends and subdivided by vertical partitions terminating at.

a point normal to the buoyancy unit interior waterline, means to add andmeans to withdraw air from said subdivided supplementary compartmentsuch that it may a function at will as a buoyancy unit in good weatherand as a water ballast compartment in bad weather, means automaticallyrecording the level of water ballast in said compartments.

23. A marine vessel having a fully displaced hull at sea and beingsubstantially fiat bottomed, a means for substituting air skin frictionfor water skin friction comprising contiguous longitudinal open bottomducts having parallel spaced vertical walls disposed on the underside ofsaid hull and intersecting the water surface, said walls being spannedat intervals by transverse partitions inclined to the sea flow to form aseries of open bottom compartments containing air in a static condition,said transverse partitions being rigidly secured to said hull andterminating at the water level, within said ducts, in a spring loadedflap capable of flexing to the horizontal under the pressure of seawater flow, a source of compressed air communicating with saidcompartments, valve means for said compressed air operatively connectedwith said spring loaded flap and operating by the flexing of said flapto replenish air losses within said compartments.

References Cited UNITED STATES 'PATENTS 1,621,625 3/1927 Casey.1,819,216 8/1931 Warner. 3,146,752 9/1964 Ford. 3,198,274 8/1965Cocksedge. 3,288,236 11/ 1966 Padial.

FOREIGN PATENTS 232,436 12/1959 Australia.

ANDREW H. FARRELL, Primary Examiner U.S. Cl. X.R.

